While I was writing a status update today on social media I decided to do some grammar-learning. The status update was "Happy Labor Day everyone!" and I am now wondering if I should place a comma between "Day" and "everyone?" My grammar skills aren't great, and this may be staring me right in the face as I'm thinking about it, but researching on the web and Stack Exchange hasn't brought up the case yet. Help would be much appreciated.
Yes! Necessary but declining in popularity. It's called a "vocative" comma, and it saves the reader from a double take in situations like "Awesome pants, Bill!" vs. "Awesome Pants Bill!" (noting the arrival of Bill, who is widely known and titled by his awesome pants).